rust: peek_mut optim for lazy ancestors
This is one of the two optimizations that are also
present in the Python code: replacing pairs of pop/push
on the BinaryHeap by single updates, hence having it
under the hood maintain its consistency (sift) only once.
On Mozilla central, the measured gain (see details below)
is around 7%.
Creating the PeekMut object by calling peek_mut() right away
instead of peek() first is less efficient (gain is only 4%, stats
not included).
Our interpretation is that its creation has a cost which is vasted
in the cases where it ends by droping the value (Peekmut::pop()
just does self.heap.pop() anyway). On the other hand, the immutable
peek() is very fast: it's just taking a reference in the
underlying vector.
The Python version still has another optimization:
if parent(current) == current-1, then the heap doesn't need
to maintain its consistency, since we already know that
it's bigger than all the others in the heap.
Rust's BinaryHeap doesn't allow us to mutate its biggest
element with no housekeeping, but we tried it anyway, with a
copy of the BinaryHeap implementation with a dedicaded added
method: it's not worth the technical debt in our opinion
(we measured only a further 1.6% improvement).
One possible explanation would be that the sift is really fast
anyway in that case, whereas it's not in the case of Python,
because it's at least partly done in slow Python code.
Still it's possible that replacing BinaryHeap by something more
dedicated to discrete ordered types could be faster.
Measurements on mozilla-central:
Three runs of 'hg perfancestors' on the parent changeset:
Moyenne des médianes: 0.100587
! wall 0.100062 comb 0.100000 user 0.100000 sys 0.000000 (best of 98)
! wall 0.135804 comb 0.130000 user 0.130000 sys 0.000000 (max of 98)
! wall 0.102864 comb 0.102755 user 0.099286 sys 0.003469 (avg of 98)
! wall 0.101486 comb 0.110000 user 0.110000 sys 0.000000 (median of 98)
! wall 0.096804 comb 0.090000 user 0.090000 sys 0.000000 (best of 100)
! wall 0.132235 comb 0.130000 user 0.120000 sys 0.010000 (max of 100)
! wall 0.100258 comb 0.100300 user 0.096000 sys 0.004300 (avg of 100)
! wall 0.098384 comb 0.100000 user 0.100000 sys 0.000000 (median of 100)
! wall 0.099925 comb 0.100000 user 0.100000 sys 0.000000 (best of 98)
! wall 0.133518 comb 0.140000 user 0.130000 sys 0.010000 (max of 98)
! wall 0.102381 comb 0.102449 user 0.098265 sys 0.004184 (avg of 98)
! wall 0.101891 comb 0.090000 user 0.090000 sys 0.000000 (median of 98)
Mean of the medians: 0.100587
On the present changeset:
! wall 0.091344 comb 0.090000 user 0.090000 sys 0.000000 (best of 100)
! wall 0.122728 comb 0.120000 user 0.110000 sys 0.010000 (max of 100)
! wall 0.093268 comb 0.093300 user 0.089300 sys 0.004000 (avg of 100)
! wall 0.092567 comb 0.100000 user 0.090000 sys 0.010000 (median of 100)
! wall 0.093294 comb 0.080000 user 0.080000 sys 0.000000 (best of 100)
! wall 0.144887 comb 0.150000 user 0.140000 sys 0.010000 (max of 100)
! wall 0.097708 comb 0.097700 user 0.093400 sys 0.004300 (avg of 100)
! wall 0.094980 comb 0.100000 user 0.090000 sys 0.010000 (median of 100)
! wall 0.091262 comb 0.090000 user 0.080000 sys 0.010000 (best of 100)
! wall 0.123772 comb 0.130000 user 0.120000 sys 0.010000 (max of 100)
! wall 0.093188 comb 0.093200 user 0.089300 sys 0.003900 (avg of 100)
! wall 0.092364 comb 0.100000 user 0.090000 sys 0.010000 (median of 100)
Mean of the medians is 0.0933
Differential Revision: https://phab.mercurial-scm.org/D5358
# Test the plumbing of mq.git option
# Automatic upgrade itself is tested elsewhere.
$ cat <<EOF >> $HGRCPATH
> [extensions]
> mq =
> [diff]
> nodates = 1
> EOF
$ hg init repo-auto
$ cd repo-auto
git=auto: regular patch creation:
$ echo a > a
$ hg add a
$ hg qnew -d '0 0' -f adda
$ cat .hg/patches/adda
# HG changeset patch
# Date 0 0
# Parent 0000000000000000000000000000000000000000
diff -r 000000000000 -r ef8dafc9fa4c a
--- /dev/null
+++ b/a
@@ -0,0 +1,1 @@
+a
git=auto: git patch creation with copy:
$ hg cp a b
$ hg qnew -d '0 0' -f copy
$ cat .hg/patches/copy
# HG changeset patch
# Date 0 0
# Parent ef8dafc9fa4caff80f6e243eb0171bcd60c455b4
diff --git a/a b/b
copy from a
copy to b
git=auto: git patch when using --git:
$ echo regular > regular
$ hg add regular
$ hg qnew -d '0 0' --git -f git
$ cat .hg/patches/git
# HG changeset patch
# Date 0 0
# Parent 99586d5f048c399e20f81cee41fbb3809c0e735d
diff --git a/regular b/regular
new file mode 100644
--- /dev/null
+++ b/regular
@@ -0,0 +1,1 @@
+regular
git=auto: regular patch after qrefresh without --git:
$ hg qrefresh -d '0 0'
$ cat .hg/patches/git
# HG changeset patch
# Date 0 0
# Parent 99586d5f048c399e20f81cee41fbb3809c0e735d
diff -r 99586d5f048c regular
--- /dev/null
+++ b/regular
@@ -0,0 +1,1 @@
+regular
$ cd ..
$ hg init repo-keep
$ cd repo-keep
$ echo '[mq]' > .hg/hgrc
$ echo 'git = KEEP' >> .hg/hgrc
git=keep: git patch with --git:
$ echo a > a
$ hg add a
$ hg qnew -d '0 0' -f --git git
$ cat .hg/patches/git
# HG changeset patch
# Date 0 0
# Parent 0000000000000000000000000000000000000000
diff --git a/a b/a
new file mode 100644
--- /dev/null
+++ b/a
@@ -0,0 +1,1 @@
+a
git=keep: git patch after qrefresh without --git:
$ echo a >> a
$ hg qrefresh -d '0 0'
$ cat .hg/patches/git
# HG changeset patch
# Date 0 0
# Parent 0000000000000000000000000000000000000000
diff --git a/a b/a
new file mode 100644
--- /dev/null
+++ b/a
@@ -0,0 +1,2 @@
+a
+a
$ cd ..
$ hg init repo-yes
$ cd repo-yes
$ echo '[mq]' > .hg/hgrc
$ echo 'git = yes' >> .hg/hgrc
git=yes: git patch:
$ echo a > a
$ hg add a
$ hg qnew -d '0 0' -f git
$ cat .hg/patches/git
# HG changeset patch
# Date 0 0
# Parent 0000000000000000000000000000000000000000
diff --git a/a b/a
new file mode 100644
--- /dev/null
+++ b/a
@@ -0,0 +1,1 @@
+a
git=yes: git patch after qrefresh:
$ echo a >> a
$ hg qrefresh -d '0 0'
$ cat .hg/patches/git
# HG changeset patch
# Date 0 0
# Parent 0000000000000000000000000000000000000000
diff --git a/a b/a
new file mode 100644
--- /dev/null
+++ b/a
@@ -0,0 +1,2 @@
+a
+a
$ cd ..
$ hg init repo-no
$ cd repo-no
$ echo '[diff]' > .hg/hgrc
$ echo 'git = True' >> .hg/hgrc
$ echo '[mq]' > .hg/hgrc
$ echo 'git = False' >> .hg/hgrc
git=no: regular patch with copy:
$ echo a > a
$ hg add a
$ hg qnew -d '0 0' -f adda
$ hg cp a b
$ hg qnew -d '0 0' -f regular
$ cat .hg/patches/regular
# HG changeset patch
# Date 0 0
# Parent ef8dafc9fa4caff80f6e243eb0171bcd60c455b4
diff -r ef8dafc9fa4c -r a70404f79ba3 b
--- /dev/null
+++ b/b
@@ -0,0 +1,1 @@
+a
git=no: regular patch after qrefresh with copy:
$ hg cp a c
$ hg qrefresh -d '0 0'
$ cat .hg/patches/regular
# HG changeset patch
# Date 0 0
# Parent ef8dafc9fa4caff80f6e243eb0171bcd60c455b4
diff -r ef8dafc9fa4c b
--- /dev/null
+++ b/b
@@ -0,0 +1,1 @@
+a
diff -r ef8dafc9fa4c c
--- /dev/null
+++ b/c
@@ -0,0 +1,1 @@
+a
Test how [diff] configuration influence and cause invalid or lossy patches:
$ cat <<EOF >> .hg/hgrc
> [mq]
> git = AUTO
> [diff]
> nobinary = True
> noprefix = True
> showfunc = True
> ignorews = True
> ignorewsamount = True
> ignoreblanklines = True
> unified = 1
> EOF
$ echo ' a' > a
$ hg qnew prepare -d '0 0'
$ echo ' a' > a
$ printf '\0' > b
$ echo >> c
$ hg qnew diff -d '0 0'
$ cat .hg/patches/prepare
# HG changeset patch
# Date 0 0
# Parent cf0bfe72686a47d8d7d7b4529a3adb8b0b449a9f
diff -r cf0bfe72686a -r fb9c4422b0f3 a
--- a/a
+++ b/a
@@ -1,1 +1,1 @@
-a
+ a
$ cat .hg/patches/diff
# HG changeset patch
# Date 0 0
# Parent fb9c4422b0f37dd576522dd9a3f99b825c177efe
diff --git a/a b/a
--- a/a
+++ b/a
@@ -1,1 +1,1 @@
- a
+ a
diff --git a/b b/b
index 78981922613b2afb6025042ff6bd878ac1994e85..f76dd238ade08917e6712764a16a22005a50573d
GIT binary patch
literal 1
Ic${MZ000310RR91
diff --git a/c b/c
--- a/c
+++ b/c
@@ -1,1 +1,2 @@
a
+
$ cd ..